package com.anlu.concurrent.ch4.aqs;

import com.sun.xml.internal.ws.client.BindingProviderProperties;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

/**
 * <p>
 * Description:实现一个自己的类ReentrantLock
 * <p>
 * Copyright: 天津联想协同科技有限公司
 * <p>
 *
 * @author anlu
 * @date 2021/9/8 11:01
 */
public class SelfLock implements Lock {

    /**
     * state表示获取到了锁， state = 1获取到了锁，state=0,表示这个锁当前没有线程拿到
     */
    private static class Sync extends AbstractQueuedSynchronizer{
        //是否占用
        @Override
        protected boolean isHeldExclusively() {
            return getState()==1;
        }

        @Override
        protected boolean tryAcquire(int arg) {
            if(compareAndSetState(0,1)){
                setExclusiveOwnerThread(Thread.currentThread());
                return true;
            }
            return false;
        }

        @Override
        protected boolean tryRelease(int arg) {
            if(getState()==0){
                throw  new UnsupportedOperationException();
            }
            setExclusiveOwnerThread(null);
            setState(0);
            return true;
        }
        Condition newCondition() {
            return new ConditionObject();
        }
    }


    private final Sync sync = new Sync();

    @Override
    public void lock() {
        sync.acquire(1);
    }

    @Override
    public void lockInterruptibly() throws InterruptedException {
        sync.acquireInterruptibly(1);
    }

    @Override
    public boolean tryLock() {
        return sync.tryAcquire(1);
    }

    @Override
    public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
        return sync.tryAcquireNanos(1, unit.toNanos(time));

    }

    @Override
    public void unlock() {
        sync.release(1);
    }

    @Override
    public Condition newCondition() {
        return sync.newCondition();
    }
}
